The long-term objective of this proposal is to gain an understanding of the intracellular signaling pathway(s) used by bacterial components. Bacterial components such as endotoxin (LPS) and lipoproteins, contribute to the pathogenesis of septic shock. This is, at least in part, by stimulating the production of pro-inflammatory cytokines, bioactive lipids, degradative enzymes, etc., from macrophages and other cells. Great progress has been made in the past few years in defining the Toll-like receptor family (TLRs) proteins which function as the primary receptors for many bacterial components. However, there is a gap in our knowledge regarding the link between TLR-initiated signaling and the downstream signaling pathways such as the p38, ERK, JNK, and NF-kappaB pathways, which are the known pathways essential in cytokine production. The work from this and other laboratories suggests that though there is clearly a similarity among the signaling initiated by different TLRs, there are distinctions downstream of TLRs. The major focus here is to define and compare the signaling events used by different TLRs in activating the p38, ERK, JNK, and NF-kappaB pathways in macrophages. To do this we will utilize a combination of genetic, biochemical, and molecular biologic approaches. The proposed work in this application will contribute to the eventual definition of the signaling pathways activated by bacterial components. Understanding the mechanisms for bacterial components-induced cellular responses will help to develop therapeutic procedures for the treatment of septic shock.